Ken Clarke leaves Downing Street after being appointed justice secretary by the prime minister. But will he listen? Photograph: Akira Suemori/AP

Welcome, Ken Clarke, to the top turret at the monolithic Ministry of Justice. Have you had your hearing checked lately? You'll have to listen hard for the voices, whispering from the ground far below you that offer solutions to the problems you face: bulging prisons, a burgeoning crime rate, repeat offending, and interventions that cost a lot while changing little.

The voice of the offender is also the voice of poverty, of the marginalised, the lost and the abused. This voice has been unheard for a long time. There's no mechanism in place to carry it to the ears of the people who can change things. Instead, successive justice ministers have been locked into a dysfunctional alignment of media and public and offenders when they should be operating in a well-informed position between all these parties. They have fought crime armed only with a Victorian strategy that is still much-loved by our backwards-looking media, a strategy that can be summed up in one word: punishment. Punishment is something one man inflicts and another receives. Punishment is deaf.

Most offenders believe wholeheartedly in punishment. They understand it. Many have been punished from the day they were born. But now that we're in the complex 21st century it's time for a new approach because, as our crime statistics prove, the old strategies change nothing.

Offenders, especially those who usually remain silent and unreached, can tell our new minister a lot about the sort of help they need to move into successful living. But listening to them is counter to the traditional concept of punishment, which is an isolating experience. Behind walls, wrapped in a punitive silence, the offender receives whatever policies, ideas and projects are thrown to him by people who have seldom attempted to understand his landscape.

Policymakers and commissioners who want to change things but don't know how to are rarely exposed directly to the people they are trying to help, perhaps because there's an industry keeping them apart. When Clarke makes the inevitable cuts, it's this fat interception industry that should starve. Even the third sector is bloated with instruments to serve itself. Don't get me wrong, some do much-needed work but, let's face it, with this lot on board what money can be left for delivery?

I believe it's time for a new model. We can start by taking the unfiltered voice of those in need directly to those who can help them – not only to policymakers and commissioners but to the well-meaning and well-heeled giver. I've met countless millionaires in the last few years who are anxious to donate to society. Their generosity makes them helpless targets for the glitzy presentations, celebrity appeals and ego-stroking evenings that some big charities have turned into an art form. With limited time and unbounded goodwill, the millionaire wants to believe the assurances that his money will make a difference. I fear that sometimes little of it reaches the frontline, while too much is spent on taxis and meals for the industry that rests on the backs of voiceless service users.

Ministers should also be the champions of thorough project evaluation. We should broaden our methods of measurement to recognise that the true impact of a project might not show by current narrow methods of analysis and it might not be felt for years.

So how can we devise projects effectively? How can we measure them? How can we cut costs and give funders value for money? The answer: engagement.

By engaging directly with those who need such help, a brave justice secretary could be the engine of change. If Clarke and his junior ministers listen hard to the voice of need, change could come quickly, effectively and, yes, economically.

• Mark Johnson, a rehabilitated offender and former drug user, is an author and the founder of the charity Uservoice.